Centrifugal clutch assembly



Jan. 16, 1962 T. FAWICK 3,017,004

CENTRIFUGAL CLUTCH ASSEMBLY Filed Dec. 30, 1958 INVENTOR. THOMAS L.FAWICK i2 26 FIG. 3 wMAZSZN ATTORNEY United States 3,017,004 CENTRIFUGALCLUTCH ASSEMBLY Thomas L. Fawick, Cleveland, Ohio, assignor to Fawick;

This invention relates to centrifugal clutches of the type in which aset of circumfercntially spaced balls or the like are urged outwardly bycentrifugal force and thus wedge apart axially a pair of clutchelements, for clutch engagement.

Its chief objects are to provide a simple and highly compact clutchstructure; to provide a clutch in which the driven clutch structure canbe within the confines of the driving structure; to provide a clutchhaving two planes of frictional engagement well spaced apart axially forshared transmission of the torque at the two wide-span positions; tohave annular Zones of frictional engagement at each side of thecentrifugal mechanism, axially of the assembly, so that wear of thefrictional engagement surfaces will not result in excessive axialshifting of the positions of the elements of the centrifugal mechanism;to provide a clutch having the centrifugal mechanism well enclosed byclutch elements free of dangerous projections or crevices; to provide inan improved manner for circumferential distribution of the wear of thesurfaces with which the centrifugal members contact in their wedgingaction; to provide a clutch having relatively light driving elements,for low inertia load; and, with regard to the last mentioned object andwith regard to other features of the assembly, to provide a clutchespecially well adapted for mounting on the motor shaft of a constantspeed electric motor.

Of the accompanying drawings:

FIG. 1 is an axial section of an assembly embodying my invention in itspreferred form for a small or light duty clutch.

FIG. 2 is a section on line 22 of FIG. 1.

FIG. 3 is a fragmentary axial section of a modification.

Secured upon the driving shaft 10, with a key 11, is a driving member 12having a sleeve hub portion 12a and a clutch-disc portion 12b. Journaledon the hub portion 12a for frictional coaction with the clutch-discportion 12b is a driven clutch member 13, here shown as being of thesame maximum diameter as the driving member 12 and formed in its outerface with V-belt grooves 13a, 13a. The driven clutch member 13 carriesroller bearings 13c which engage the hub 12a rotatably and alsoslidably, thereby enabling the driven clutch member to be moved axiallyalong hub 12a.

Axially slidable with relation to the driven member 13 but interlockedwith it by interfitting jaws at 14a against relative circumferentialmovement is a clutch ring 14 which is held centered by a thincylindrical ring 15 pressfitted or otherwise mounted at one of its endsupon the adjacent end of the driven belt-pulley member 13. The clutchring 14 is adapted for frictional coaction with a driving clutch-disc 16which is splined upon the sleeve hub 12a and retained thereon by alock-washer 1'7 and a nut 18.

The driving members 12 and 16 and the respective driven members areprovided with means on certain of said members for clutching engagementbetween the axi ally inward ends of both driving members 12 and 16 andthe axially outward ends of the respective driven members 13 and 14. Asshown in FIGURE 1, such clutching engagement means are constituted by anannular disk 30 of friction material on the axially inward end ofdriving ice member 12 and a similar friction disk 31 on the axiallyinward end of driving member 16.

The hub portions of the driven member 13 and the driving disc 16 are ata distance from each other axially of the assembly and between them aball-impelling ring 19, preferably of a self-lubricating or inherentlyslippery material such as nylon, is slipsplined upon the sleevehubelement 12a.

The outer periphery of the ball-impelling ring 19 is of outwardlynarrowing form and is formed with a set of evenly spaced ball socketsdefined by intervening ballimpelling fingers 20, 20 for compellingrespective balls 21, 21 to rotate with the ring 19 and thus developcentrifugal force for coacting with conical annular surfaces 13b, 1412on the members 13 and 14 respectively for forcing those members apartaxially and thus effecting the clutch engagement.

Preferably the floor of each ball socket is spherical and complementaryto the surface of the ball, for centering the ring 19 in relation to theballs in the return movement of the balls toward the axis of rotation,and preferably the ring, along the sockets, is of less axial thicknessthan the ball diameter, so that as the balls are moved outward fromtheir seats by the centrifugal force they can immediately equalize theirpressures against the sloping faces 13b, 14b.

Return Springs are not shown because in the case of a centrifugal clutchmounted upon the shaft of a constant speed electric motor the operationof the driven machine usually is stopped by turning off the motor andthus there is no need for otherwise terminating the effectiveness of thecentrifugal force.

The faces 13]), 14b of course converge outwardly at a large enough angleto avoid the presence of an angle of repose that would cause the ballsto stay strongly wedged between those surfaces after the turning off ofthe motor.

In the structure described, the cam surfaces 13b and 14b both being ondriven elements and having the same cone angle, and being compelled bythe jaws at 1411 to rotate at the same speed, the balls can have freeand equal rolling contact with the faces 13!; and 14b while engagementof the clutch is bringing the driven elements up to full speed.

Slip contacts of the balls with the nylon ring do not result insubstantial wear or loss of power, because of the slippery character ofthe nylon and because only a small amount of force is at any timeexerted between the nylon ring and the balls. Also, because of thealways even speed of the faces 13b, 14b of the two driven elements,there is very little or practically no slip contact between the ballsand the nylon ring, such as would cause wear or power loss, becausesubstantially the only pressure of the free-rolling balls against thering is their inertia pressure during their acceleration.

The modification shown in FIG. 3 embodied features that are claimed inmy copending application Ser. No. 782,480, filed December 23, 1958. Inthis modification the nylon cam-impelling ring, 19a, is loose-journaledon and between a pair of cross sectionally L-shaped frictiondrive rings22, 23 which are splined on the adjacent driving sleeve hub 12a and ofwhich the ring 22 is held against leftward axial movement by astop-shoulder on said hub. A set of compression springs, such as thespring 24, areinterposed between the ring 23 and the clutch-discelement, 12m, which is formed with suitable spring-seat sockets asshown. For varying the frictiondrive pressure of the springs against thefriction-drive ring 23, respective adjusting screws, such as the screw25, are threaded through the end walls of the respective spring-seatsockets, bear against respective spring seat discs, 26, slidably mountedin the sockets, and on the 3 outer side of the element 12m are providedwith respective holding nuts, 27.

In this embodiment the ring 19a is driven frictionally by the rings 22,23, and adjustment of the friction-drive pressure is provided, forvarying the quickness of clutch engagement, by the adjusting screws.

The invention has the advantages that are set forth in the abovestatement of objects and other modifications are possible withoutsacrifice of all of those advantages and with departure from the scopeof the invention as defined in the appended claims.

I claim:

1. In a centrifugal clutch assembly, the combination of a rotary inputdrive element, a pair of axially spaced rotary driving members coupledto said input drive element to be driven thereby, a pair of rotatabledriven members mounted between said driving members, at least one ofsaid driven members having a substantial axial thickness so that saiddriven members space said driving members apart a substantial distanceaxially, said driven members being coupled to each other to rotate inunison and being movable axially with respect to one another, means oncertain of said members for clutching engagement between the axiallyinward ends of both driving members and the axially outward ends of therespective driven members when the driven members are moved axiallyapart from one another and toward the respective driving members, saiddriven members at their axially inward ends presenting axially spacedapart, confronting annular cam faces which converge toward each other ina radially outward direction and which define between them an annularcam space which is progressively narrower radially outward, a rotatablecam carrier, and a plurality of circumferentially spaced cams carried bysaid cam carrier in said cam space for engagement with said cam facessaid cam carrier being coupled to said input drive element to be rotatedthereby independent of the engagement of said cams with said drivenmembers, said cams being mounted on said cam carrier to turn therewithin said cam space and to move outward centrifugally in response to therotation of the cam carrier to force said driven members axially apartfrom each other and into clutching engagement with said driving members.

2. The clutch assembly of claim 1 wherein said cam carrier is coupleddirectly to said input drive element to rotate therewith.

3. The clutch assembly of claim 1 wherein there is provided frictionclutch means coupling said cam carrier to said input drive element.

4. The clutch assembly of claim 1 wherein said one driven member whichhas a substantial axial thickness is exposed at its periphery andconstitutes a pulley for driving a belt.

References Cited in the file of this patent UNITED STATES PATENTS1,092,015 Bryant Mar. 31, 1914 1,618,644 Dickson Feb. 22, 1927 1,766,227Russell June 24, 1930 1,801,590 Dickson Apr. 21, 1931 1,889,291 PirinoliNov. 29, 1932 1,994,588 Nakashian Mar. 19, 1935 2,180,217 Thomas Nov.14, 1939 2,753,967 Bowers July 10, 1956 FOREIGN PATENTS 283,380 GreatBritain a- Jan. 12, 1928 1,024,294 Germany Feb. 13, 1958

